Brake-shoe key



Patented Apr. 10, 1923.

j UNITED 'STATES P OFECE.

BRAKE-SHOE KEY.

Application filed April 28, 1922. Serial No. 557,118.

10 all whom t may concern:

Be it known that I, ERAsTUs EMERY, re` siding at Pittsburgh, in the county of Alle glieny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Brake-Shoe Keys, of which improvements the following is a specification.

Itis the general practice to securebrakeshoes to brake-shoe heads by means of keys passing throughlugs on the shoes and heads, it being the general practice to form two lugs on the head suitably spaced and one lug on the shoe adapted to pass between the lugs on the head. The inner surfaces of these lugs against which the key will bear when in locked position, are made on arcs of .circles, and by general consent the curvature of these surfaces as well as dimensions of the shoes and heads have been standardized, as also the thickness and curvature of the tapering pin employed for locking the head to the shoe. As this pin -or key is usually formed by forging a rolling, it can be given the exact standard dimensions and curvature. But as the heads and shoes are made by casting, it is practically impossible to insure that the stan dard dimensions will be complied with at all times', and hence a certain allowance is made in the dimensions of the parts of the shoe and head. By reason of the construction above specified, the key will have only a line bearing on the inner surfaces of the lugs of the shoes and headsand even if the dimensions and curvature of the lugs should conform to standard, the key Vis liable vto work loose on account of its taper and also because it is substantially narrower than the widths of the openings through the lugs on the brake shoe head and shoe. If the dimensions of the lugs do not conform to standard, then the liability of the keys working loose is increased.k

The construction described and claimed herein has for 'its object a construction of key whereby the latter may bear on the lugs of the head, while a portion which is intended to bear against the lug on the head is so constructed that a firm bearing'of the key on the lug will be insured regardless of permissible variations `of dimensions of the lugs on the shoes and head. It is a further object of the invention to so construct the key as to prevent any lateral movement of the shoe on'Y the head.v rlhe invention is hereinafter more `fully described and claimed.

In the accompanying drawings, forming a part of this specification, Fig. l is a sec* tional elevation of a brake-shoe and brakeshoe head secured together in proper relation by the improved key claimed herein; Fig. 2 is a sectional view on a plane indicated by the line II-II, Fig. l; and Fig. 3 is adetail view, showing a modification of the key.

In the practice of the invention the brakeshoe head and brake shoe are formed according to standard dimensions. The head l is provided with lugs 3 and 4l having openings ,therethrough for the passage of the key and adjacent to its upper and lower ends with abutments 5 against which the shoe will bear when in position on the head. The brake shoe is provided with a lug 6 having an opening therethrough and adapted to project when the shoe is` placed in position against the head between the lugs 3 and 4 on the head. In thestandard construction the bearing` surfaces a of the lugs 3 and 4 and the bearing surface b of therlug 6 are formed on arcs of concentric circles and hence the surfaces a will, if the head conforms to standard dimensions, be parallel with the surface b on the shoe, if also of standard dimensions, so that if a key, tapering from end to end, and having the same curvature longitudinally as that of the surfaces a and b of the head and shoe as in the present construction, were forced in through these lugs to lock the shoe in position, the key would have only line bearings on the respective lugs. If there were a departure, either from' the curvature of these surfases on the head and shoe respectively, or if these surfaces did not conform to the standard as regards their positions relative to each other and to the abutments 5, then the key when forced to its position would not bear in such manner on the surfaces of the lugs as to form an effective and permanent. lock. The improved key is made of substantially uniform thickness from end to end, such thicknessI being slightly less than the distances between planes coincident with? the surfaces a and the surfaces In the construction shown in Figs. l and 2 the key'isformed by bending a llo thus formed are curved longitudinally, such curvature corresponding or approximately corresponding to the curvature of surfaces a of the lugs 3 and a of the head and that ot' the surfaces Z5 of the lugs on the shoe. Adjacent to their ends the legs are provided with inclined shoulders ll preferably formed of outwardly bending legs and the portions 12 beyond the `lshoulders are so inclined inwardly that the distance between the ends of the portions l2 would be somewhat less than the widths ot the slots or openings through the lugs on the head and shoe. These inwardly inclined portions are designed to facilitate the insertion oi' the key to locking position. Then the key is driven in. the legs will be compressed until the shoulders pass beyond the lug 3 on thc head, whereupon the legs will spring apart, the shoulders ll jmssingl behind the lug 3 on the head, thereby effectu'ally locking the key as against movement in an unlocking direction. The legs ext-end from the body portion l() with some divergence which is so proportionedvthat when the key has been iuserted in the shoulders 11 and have passed beyond the lug 3 allowing the legs to spring apart, the outer surfaces ot' the legs will bear against the Sides of the slots or openings through the lugs on the head and shoe and thus prevent any lateral moven'xent ot' the shoe relative to the head.

vThe legs oi the key have portions c and Z spaced suoli a distance apart that they will bear on the surfaces a of the lugs 3 anda Jfor a substantial extent when the key is in locking position. The portion e of the key intermediate these spaced portions c and (Z is off-set in such manner as to 'form inclined surfaces Vwhich will be tangential or approximately tangential to the longitudinal curvature of the legs and will operate as wedges bearing against the surface of the lug on the shoe. This portion is oit-set to such a degree that no matter how much the lugs may depart from standard dimensions, provided such departure is not greater-than that allowed, these offset portions will bear against the lug 6 and portions on opposite sides ot the off set will bear uniformly on the surface a ot the lugs 3 and d. The inclined portions e are so located with relierence to the shoulders 1l that when the distance between a plane coincident with the surfaces ai of the lugs 3 and t and a plane coincident with the surface Y) ot the lug 6 correspondwith a peiniss'ible departure be'- low the standard, the inclined port-ions e will enter a short distance. into the slots in t-.he lug on the shoe when the shoulders ll have passed behind the lug 3. It the dimensions of the head and-shoe are standard or greater to a permissible extent, the inclined surfaces e will move farther into the slotsor openings in the lug 6. As the head and shoe are always in a substantially vertical position, the jarring to which they are subjected will cause the key to drop down until the inclined portions e bear against the lug 6.

In lieu of forming the key by bending` a strip of metal as above stated, the key may! be forged or stamped as shown in Fig. 3, the portion adjacent to the loop or handle 9a being solid or integral and the lugs diverging from this solid or integral portion. In other respects, the key will be constructed substantially similar t0 the key shown in Figs. l and 2.

The improved key consists ot a body portion which includes the loop or head 9 and the portion lO or l0a in the respective forms and resilient legs extending preferably in diverging lines from the body portion. The

.downward movement oi the key will always be limited either by the inclined surfaces e or by the head or loop 9, and its outward movement in locking position would be prevented byi the shoulders l1. Then the key is in locking position, all portions thereotl except the head or loop 9 are inaccessible and the key will be withdrawn only by an upward pull exerted on the head'7 which as stated, is provided with a loop or opening for the insertion of a bar or other tool when it is desired to withdraw the key.

It has heretofore been customary to form a lip on the upper end of' the key, such loop being at right angles to the general plane of the key. This construction permits of the key moving down until the lip will strike against the lug on the shoe-head. In the construction shown herein the head 9 lies in the general plane of the key but projects laterally therefrom so that it will strike against the abutments 5 on the shoehead and prevent any further movement downwardly of the key. It is characteristic of the improvement claimed herein that the portion of the key intermediate of the head 9 and the shoulders 11 on the lugs, is formed of a length approximately equal to the dis` tance between the outer surface of the upper abutments 5 on the head and the lower lug B, so that the key when in operative position. cannot move any material distance longitudinally either up or down. And further, the body portion is made of such a length between its head and the point of junction of the legs therewith that the legs will have a resilient bearing against the side walls of" the openings through the lugs on the shoehead and shoe, thus preventing any lateral movement of the shoe on the head.

Experience has shown that if the key were made U-shape, a blow on the closed end, unless directly in line with the key, would cause the leg most nearly in-line with the blow to move down further than the other leg and the key willbe distorted. This diiiilll) lli',

culty has been overcome by bringing the legs into contact immediately below the closed end as shown in Figs. l and 2, or making the legs integral as shown in Fig. 3. It has been found that even if the driving blow is not central 0r in line with the legs, the lattei` would move down uniformly and Without distortion.

I claim herein as my invention:

l. A key for connecting a brake shoe to a brake shoe head having in combination a body portion and resilient legs extending from the body portion, said legs being curved longitudinally and having spaced portions adapted to bear uniformly on lugs on the shoe-head and a portion intermediate the spaced portions soolfset as to form inclined surfaces tangential or approximately tangential to the curvature of the legs for engagement with the lug on the shoe.

2. A key for connecting brake shoes to brake shoe heads having in combination a bodyl portion and resilient legs extending from the body portion, said legs being curved longitudinally and having spaced portions adapted to bear uniformly on lugs on the shoe-head and a portion intermediate the spaced portions so oset as to form inclined surfaces tangential or approximately tangential to the curvature of the legs for engagement with the lug on the shoe, the free ends of the legs being separated a distance greater than the widths of the openingsin the lugs and provided with inclined shouli ders adapted to engage one of the lugs on the head and prevent longitudinal unlocking movement of the key.

3. A key forconnecting a brake shoe to a brake shoe head having in combination resilient legs, a loop integrally connecting the legs at one end, said legs being substantially in contact adjacent to the loop forming the body portion, the portions of the legs extending from the body portion being'curved longitudinally and adapted when in operative position te bear against the side walls of the openings through the lugs on the head and shoe, and inclined shoulders on the legs adjacent to their lower ends, the legs having spaced portions adapted to bear on the lugs on the head and portions intermediate the spaced portions so offset as to form inclined surfaces tangential or approximately tangential to the curvature of the legs for engagement with the lug on the shoe.

4. A keyl connecting a brake-shoe to a brake-shoe head, said head and shoe having intercalating lugs intermediate their ends, said lugs having openings therethrough having in combination an upper body portion, resilient legs extending from the body portion and adapted to bear, when the key is in operative position, against the side walls of the Openings through the lugs on the shoe head and shoe, and a head at the upper end of the key adapted to prevent the key from such longitudinal movement as will move the legs from a bearing with the upper lug on the head.

5. A key for connecting a brake shoe to a brake shoe head, said head and shoe having intercalating lugs intermediate their ends, said lugs having openings there-4 through having in combination an upper body portion, resilient legs extending from the body portion and adapted when the key is in operative position tobear against the side walls of the openings through the lugs on the shoe-head, a head on the body portion and shoulders adjacent to the ends of the legs, said shoulders and head being adapted when the key is in operative position, to maintain the legs in contact with the side walls of the openingsthrough the lugs on the head and shoe.

6. A key for connecting a brake shoe to a brake shoe head, said head and shoe having intercalating lugs intermediate their ends, said lugs having openings therethrough having in combination a body portion, a head extending laterally from the body portion, resilient legs extending from the body portionand adapted when the key is in operative position to bear against the side walls of the openings through the lugs on the shoe head and shoe. and shoulders ad- .jacent to the lower ends of the legs, the portions Of the legs beyond the shoulders being inwardly inclined.

7. A key for connecting a brake shoe to a brake shoe headfhaving in combination resilient legs, a loop integrally connecting the legs at one end, said legs being substantially in contact adjacent to the loop, thereby forming a body portion and the loop extending laterally from the upper end of the bodyl portion to form a head, the portions of the legs 'beyond the body portion being adapted, when the key is in operative position, to bear against the side walls of the openings through the lugs on the brake shoe head and shoe.

8. A key for connecting a brake shoe to a brake shoe head having in combination resilient legs, a loop integrally connecting the legs at one end, said legs being substantially in contact adjacent tothe loop, thereby forming a body portion and the loop extending laterally from the upper end of the body portion to form a head, the portions of the legs beyond the body portion being adapted,

when the keyl is inoperative position, to bear against the side walls of the openings through the lugs on the brake shoe head and shoe, and inclined shoulders on the legs adjacent to the lower free ends thereof.

'In testimony whereof, I have hereunto set my hand.

ERAS-TUS EMERY. 

